A numerical solution for the free convective, unsteady, laminar convective
heat and mass transfer in a viscoelastic fluid along a semi-infinite vertical
plate is presented. The Walters-B liquid model is employed to simulate
medical creams and other rheological liquids encountered in biotechnology and
chemical engineering. This rheological model introduces supplementary terms
into the momentum conservation equation. The dimensionless unsteady, coupled
and non-linear partial differential conservation equations for the boundary
layer regime are solved by an efficient, accurate and unconditionally stable
finite difference scheme of the Crank-Nicolson type. The velocity,
temperature and concentration fields have been studied for the effect of
Prandtl number (Pr), viscoelasticity parameter (G), Schmidt number (Sc),
Buoyancy ration parameter (N). The local skin-friction, Nusselt number and
Sherwood number are also presented and analyzed graphically. It is observed
that, when the viscoelasticity parameter (G) increases, the velocity
increases close to the plate surface. An increase in Schmidt number is
observed to significantly decrease both velocity and concentration.